Did God Create Flesh-Eating Bacteria? A Creation Model for the Origin of Human Disease

March 1, 2010

By Dr. Fazale Rana

“How are flesh-eating bacteria consistent with an all-powerful, all-loving God?” This question was posed to me on a recent episode (January 19, 2010) of our I Didn’t Know That! podcast.

It’s a provocative, yet sensible, question. Necrotizing fasciitis (or flesh-eating disease) is a bacterial infection of the deepest layers of the skin and subcutaneous tissues. The infection consists of either several microbial species (Type I) or a single species (Type II). A number of different bacteria cause this gruesome disease including: Streptococcus pyogenes, Staphylococcus aureus, Vibrio vulnificus, and Clostridium perfringens.

Despite the name, flesh-eating microbes don’t really eat flesh. Instead, they destroy tissue near the site of infection by releasing toxins. This tissue destruction yields the repulsive, superficial appearance of the skin and muscle being consumed by the bacteria.

Did God create bacteria to infect humans and cause diseases like necrotizing fasciitis? Are these microbes part of God’s good creation? Such queries highlight the need to augment our creation model to formally include an explanation for the origin of human diseases.

Foundational Tenets

Two ideas form the basis for the model.

Microorganisms can be understood as part of God’s good design. Although people commonly think of microbes in a negative light, they actually play a key role in ecosystems and in maintaining human health. As a case in point, viruses function critically in cycling nutrients in the oceans. These microbes infect and destroy other microorganisms, resulting in the release of nutrients into the ecosystem.1 Viruses are also useful in biomedical applications like gene therapy.2 The properties that make viruses infectious are the same characteristics that make them suitable for gene therapy. In this sense, viruses could be understood as part of God’s providential care for humanity.

Additionally, bacteria help maintain human health. Scientists now possess the tools to characterize (identify) the microbial flora associated with the human body. Over 100 trillion bacterial cells occupy the exterior and interior surfaces of humans. (For reference there are about 10 trillion cells that comprise the human body.) Estimates indicate that over a thousand bacterial species exist in the human gut, a few hundred in the mouth, and around one hundred species on the human skin. (Interestingly, there are only about one hundred pathogenic species of bacteria.) In fact over 99% of the genes associated with the human organism come from surface bacteria.4 (For a detailed discussion on recent work cataloguing the genes associated with the microbiome of the human gut listen to the March 5, 2010 episode of our podcast Science News Flash.)

Microorganisms can evolve. At RTB, we are skeptical of the evolutionary paradigm. From our perspective, the origin and history of life cannot be explained apart from the direct involvement of a Creator. But that doesn’t mean we necessarily reject all forms of biological evolution. It is clear that species can vary (or adapt) over time, and evidence exists that one species can give rise to a closely related sister species. There is also an abundance of evidence that microorganisms (like viruses, bacteria, and single-celled eukaryotes) evolve. It is not surprising that single-celled microbes and viruses can evolve, given their extremely large population sizes and capacity to take up large pieces of DNA from their surroundings and incorporate these biomolecular fragments into their genomes.

Creation Model for the Origin of Human Disease

While RTB scholars would maintain that God created microbes for a variety of reasons, (including parasites that infect animals and other life-forms to control their populations), he did not create corresponding human pathogens when he made human beings. We would assert, however, that he did create beneficial microbes that would form mutualistic symbiotic associations with humans by populating their exterior and interior surfaces.

But because microorganisms can evolve, our model predicts that a small fraction of the human microbiome became pathogenic over time as a consequence of mutations occurring within the context of the large population sizes. Once pathogens emerged, they could transfer their toxin-producing genes to other microbes through horizontal (or lateral) gene transfer, creating new disease-causing strains. A recent example of this process explains the emergence of the deadlyE. coli strain, O157:H7. Most strains of E. coli (found in the human gut) are harmless. The O157:H7 strain appears to have originated when toxin-encoding genes were transferred to a benign strain of E. coli from the microbe Shigella, a human pathogen.

Microbes that infect other animals would be another source of human pathogens. Again, mutations would allow these microbes to jump from the animal host to humans. Host-hopping occurs quite frequently with viruses and explains, for example, the genesis of HIV, which appears to have originated from SIV, a virus that infects chimpanzees, and SARS, which may have hopped from an avian host to humans. (Incidentally, host-jumping can work the other direction as well. Researchers recently observed that a strain of Staphylococcus aureus in poultry originated from a human host.8

So, within the framework of the RTB model, how can the origin of flesh-eating microbes specifically be explained? One possibility is that bacterial strains that cause necrotizing fasciitis in animals host-jumped to humans. Another possible explanation is that non-flesh-eating strains were associated with humans all along, but recently evolved tissue-destructive capabilities. In light of the second option, scientists from The Methodist Hospital Research Institute in Houston discovered that a single mutation decreases the virulence of a necrotizing strain of Streptococcus.9 This single change leads to a sequence of biochemical changes that reduces the amount of an enzyme, called a protease, secreted by the bacterium into the host’s tissue. This is a good thing, because proteases are enzymes that digest proteins and would degrade muscle and connective tissues. This result suggests that the reverse could have happened. Any change that initiates or increases protease secretion into the extracellular environment could cause necrosis, transforming a relatively benign microbe into a frightening killer strain.

The RTB creation model readily accounts for the origin of human diseases and at the same time allows us to view viruses, bacteria, and other human pathogens as part of God’s good creation. The capacity of microbes to evolve after they were created brought about human infectious diseases. From this perspective, the existence of flesh-eating bacteria is fully compatible with an all-powerful Creator who loves and cares for His creation. __________

Dr. Fazale Rana

In 1999, I left my position in R&D at a Fortune 500 company to join Reasons to Believe because I felt the most important thing I could do as a scientist is to communicate to skeptics and believers alike the powerful scientific evidence—evidence that is being uncovered day after day—for God’s existence and the reliability of Scripture. Read more about Dr. Fazale Rana

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